Since the Straddle's profit potential depends on its price from purchase time to expiration, the investor should be aware of the factors that affect the Straddle;s price. Several factors affect a Straddle's price. The first is, of course, stock price. The stock's price dictates the value of both components of the Straddle - the call and the put - affecting the Straddle price as a whole. As the stock price moves, the prices of the call and the put will fluctuate via the current Deltas of the options and thereby affect the price of the Straddle.

As the stock moves higher, the price of the call will increase while the price of the put decreases. They do not move linearly, meaning that as the stock continues higher, the call's value increases progressively more while the put's value decreases progressively less. This non-linear effect is because of the option's changing Delta.

The call Delta increases as the stock goes up while the put Delta decreases. This opposing effect continues until the call gains value dollar for dollar with the stock (once its Delta reaches 100) indefinitely. At the same time, the put value-loss stops because the put now has no value (as put Delta approaches 0).

The opposite is true if the stock trades down. The call will lose value progressively slower until it reaches $0. Meanwhile, the put will gain value at an increasing rate until the Delta becomes 100. Then the put will gain dollar for dollar with the stock indefinitely. The chart below illustrates the effect of stock movement on the dollar value and Delta value of the Straddle.

Again, we will use the July 65 Straddle as an example. The Straddle will be worth $4.10 ($2.10 for the call, $2.00 for the put).

Stock/ Call/ Call Delta/ Put/ Put Delta/ Straddle

57.50.42157.81-868.23

59.50.78246.16-776.94

61.501.35344.17-676.06

63.502.11453.46-565.57

65.503.13562.47-445.60

67.504.35661.69-346.04

69.505.77751.11-256.88

71.507.3783.71-178.08

73.009.0983.43.129.52

A second factor that affects the pricing of a Straddle is implied volatility. As implied volatility increases, the value of the Straddle increases. The price of both calls and puts increase as implied volatility increases. A Straddle will feel a double effect when volatility increases because the strategy employs two options working together and not against each other.

When a strategy uses two options working against each other, the effect of implied volatility on the strategy is the difference of its effect on each option. This is different from a Straddle where the two options are working together. This combines the effect of implied volatility on each option.

Implied volatility movement affects an individual option to an exact dollar amount as indicated by the option's volatility sensitivity component or Vega. An option with a $.05 Vega will increase five cents in value for every tick that implied volatility increases. It will decrease in value five cents for every tick that implied volatility decreases.

A call and its corresponding put will have the same Vega. That is, if the July 65 call has a .10 Vega, then the July 65 put will also have a .10 Vega. Remember, Vega is calculated by the strike price and does not differentiate put or call. Now that we have confirmed this concept, we can use it to calculate how much our Straddle price will change with a movement in implied volatility.

The Straddle combines a call and its corresponding put doubling the Vega effect. This means that the Vega of a Straddle is the addition of the Vega of the call and the Vega of the put. Since the put and call Vega are the same, we simply times the Vega of the strike by two.

Look back at our example. If the July 65 call has a .10 Vega, then the July 65 put must also have a .10 Vega and thus the July 65 Straddle will have a .20 Vega. This means that for every tick that implied volatility increases, the July 65 Straddle will increase $.20 in value. Conversely, for every tick that volatility decreases, the July 65 Straddle will decrease in value. The chart below shows how the Straddle-value changes at different implied volatility levels.

Price/ Vol.Level Call Put Straddle Vega

65.50303.132.475.60.174

65.50404.053.397.44.180

65.50504.964.319.27.182

65.50605.885.2311.11.184

65.50706.806.1512.95.184

When you study the chart, you can see that as implied volatility increases or decreases, the value of the Straddle increases or decreases by the amount of the Straddle's Vega multiplied by the amount of tick change in implied volatility.

Finally, time is another major factor affecting the price of a Straddle. Time takes a toll on all options. Its effect is even more pronounced on the Straddle which that combines two options for the same period. A Straddle will see twice the rate of decay that a single option will. From previous discussions, we should be familiar with the option decay chart and its non-linear curve. As time goes by, the Straddle will decay, day after day, at an ever-increasing rate until expiration Friday at 4:00 p.m.

The implication to the buyer and seller is obvious. The passage of time decreases the value of the Straddle and thus always favors the seller. Time works against the buyer. The buyer has until expiration to get either a large stock or implied volatility movement to offset the price paid for the Straddle.